1. Field of the Invention
The present invention relates to a method of making a magnet arrangement. The magnet arrangement includes a cylindrical magnet and pole shoes or pole pieces surrounding and resting against the magnet. The pole shoes are formed of hollow cylinder sections. Two cover plates are placed on the end faces of the magnet and of the pole shoes. The cover plates and the pole shoes are connected.
The present invention further relates to the magnet arrangement obtained by the method.
2. Description of the Prior Art
A magnet arrangement of this type is known from German Utility Model No. 6,750,056. In this magnet arrangement, the pole pieces are loosely placed around a magnet core. The cover plates are constructed as clamping pieces which are clamped together with pole pieces. This magnet arrangement has the disadvantage that either the inner surfaces of the pole pieces or the outer surfaces of the magnet must have a very exact finish and their radii must be adjusted to each other, in order to achieve the magnetically required full surface area contact between the inner surfaces of the pole pieces and the outer surface of the magnet. However, such an exact finishing is relatively expensive, particularly of the outer surface of the magnet. If the expense for finishing the surface is not or cannot be incurred, the magnet arrangement has the disadvantage that air gaps are created between the inner surfaces of the pole pieces and the outer surface of the magnet. This impairs the efficiency of the magnet arrangement and the linearity of the magnetic flux. In addition, the clamping connection of the cover plates with the pole pieces is difficult to manufacture and not sufficiently rigid.
German Utility Model No. 6,802,788 discloses a similar magnet arrangement which is also assembled in a similar manner, except that the cover plates are made of plastics material and the plastics material is injected in such a way that the plastics material penetrating into the recesses or undercuts of the pole shoes holds the arrangement together. The disadvantages of this magnet arrangement are essentially the same as that of the magnet arrangement disclosed in German Utility Model No. 6,750,056.
French Laid-Open Application No. 2,538,121 discloses a magnet arrangement in which the inner magnet is block-shaped. The pole pieces have a cross-section which has the shape of a segment of a circle. The front elevational view of the pole pieces is rectangular, wherein the rectangle fits together with the corresponding plane countersurface of the block-shaped magnet. After the pole pieces have been fixed in a certain position, the magnet is slid between the pole pieces. The cover plates are then placed on the magnet and pole pieces and are connected to the pole pieces by gluing or welding. Because of the different shape of the magnet, the magnet arrangement according to the French reference is not comparable to the type of magnet arrangement according to the invention. In addition, the shapes of the magnet and of the pole pieces must be finished very exactly and, therefore, this magnet arrangement has the same disadvantages as those discussed above.
It is, therefore, the primary object of the present invention to provide a method of making a magnet arrangement in which it is not necessary to meet narrow tolerances in finishing the pole shoes and particularly the magnet. In addition, in the finished magnet arrangement, no air gaps are to exist between the inner surfaces of the pole shoes and the outer surfaces of the magnet.